This invention relates to ceramic whiteware bodies, glazes for the bodies, compositions for preparing the bodies and energy efficient processes for the fabrication of the bodies.
Over the past several years the production of whiteware bodies has increased substantially in the United States. The rapidity of this growth is demonstrated by the fact that total domestic production of fine ceramics increased from an estimated 750 million dollars in 1960 to more than 1.1 billion dollars in 1970. Continuing research and development efforts to improve existing products and find new uses therefore, to develop new products and to improve production efficiencies have immeasurably contributed to the expansion of the whiteware market.
The production of tile, which comprises a substantial portion of the whiteware manufactured domestically, is exemplary of the improvements which have been realized throughout the industry as a result of such research and development endeavors. Commercial tile products are generally classified either as floor tile or wall tile and are used in and about the home in bathrooms, kitchens, terraces and swimming pools. They are also used on floors and walls of public and industrial buildings. While many floor tile bodies are triaxial with a high feldspar content, most wall tile bodies have a high talc content (60% to 80%). The firing schedules for the production of commercial tile bodies usually encompasses temperatures within the range of 1000.degree. C. to 1300.degree. C. and periods of time of several hours duration. In the past, glazes for wall tiles frequently proved to become inadequate with the passage of time due to crazing problems. More recently, however, glazes have been developed which display greatly improved resistance to crazing. Other improvements in tile production relate to appearance, strength and cost.
The preceding discussion has focused upon tile bodies for illustrative purposes only since, as previously mentioned, tile is one of the more common whiteware bodies. Obviously, similar considerations are applicable to the production and utilization of other whiteware bodies. In this regard extensive research and development work has been undertaken to ascertain ways of realizing additional cost savings in the production of whiteware products. One area that has received considerable attention is the relatively large quantities of fuel which are required to meet the firing schedules for fabrication of the multitude of whiteware products. The advent of "the energy crisis" and the concommitant substantial increases in fuel costs have caused a corresponding increase in production costs. Thus, many of the savings previously realized from improved products and manufacturing efficiencies have been partially offset by the added cost of heat. Attempts to conserve energy by producing selected whiteware products by using less intense processing conditions (i.e. altering the firing schedule by using lower temperatures or shorter times.) have been successful only on a very limited basis largely because the fabrication of a particular whiteware product requires a specific firing schedule which inherently includes a unique relationship between specific times and specific temperatures. When an altered firing schedule is employed, oftentimes, the end product does not have the desired properties.